Diborane structure has four terminal and two bridging hydrogen atoms. The simple Boron Hydride is Diborane B2H6. The structure can be explained as, electrons are required for the formation of conventional covalent bond structure, whereas in Diborane there are only 12 valence electrons, three from each Boron atoms. Thus B2H6 is an electron deficient component.
The four terminal hydrogen atoms and two boron atoms lie one plane. Above and below this plane, there are two bridging hydrogen atoms. Each Boron atom forms four bonds eventhough it has only three electrons. The terminal B-H bonds are regular bonds but the bridge B-H bonds are different. Each bridge hydrogen is bonded to the two boron atoms only by sharing of two electrons. Such covalent bond is called three centre electron pair bond or a multicentre bond or banana bond
It is a colorless gas at room temperature with a repulsively sweet odor. Diborane mixes well with air, easily forming explosive mixtures. Diborane will ignite spontaneously in moist air at room temperature. Synonyms include boroethane, boron hydride, and diboron hexahydride.